TWI838720B - Thermally conductive film adhesive, die-cutting die bonding film, semiconductor package and manufacturing method thereof - Google Patents

Abstract

The present invention provides a thermally conductive film adhesive that can fully carry out the curing reaction under more stable conditions, and when used as a die attach film, can effectively suppress the residual gap between the adhesive and the wiring substrate in the obtained semiconductor package, thereby obtaining a semiconductor package with excellent heat dissipation inside the package. In addition, the present invention provides a semiconductor package using the thermally conductive film adhesive and a manufacturing method thereof.

Description

Thermally conductive film adhesive, wafer-cutting adhesive film, semiconductor package and manufacturing method thereof

The present invention relates to a thermally conductive film adhesive, a semiconductor package and a manufacturing method thereof.

In recent years, stacked MCP (Multi Chip Package) consisting of multi-stage laminated semiconductor chips has become popular and is installed in the form of memory packages for mobile phones and portable audio and video equipment. In addition, with the multi-functionality of mobile phones, the high density and high integration of semiconductor packages have also been promoted. The multi-stage lamination of semiconductor chips has also been carried out accordingly.

In the manufacturing process of this kind of memory package, the connection between the wiring substrate and the semiconductor chip or the connection between the semiconductor chips is made using a film adhesive (die attach film, die bonding film). With the multi-stage lamination of chips, the demand for thinner die attach films has increased. In addition, in recent years, due to the miniaturization of wafer wiring rules, the surface of semiconductor components is prone to heat generation, and it is necessary to dissipate the heat to the outside of the semiconductor package. Therefore, film adhesives are also required to have high thermal conductivity.

In order to design a thin film adhesive with high thermal conductivity, a small-diameter inorganic filler (thermal conductive filler) is highly filled in the film adhesive. However, if the small-diameter thermal conductive filler is highly filled, the fluidity of the film adhesive will decrease. Due to the decrease in fluidity, when the semiconductor chip is mounted on the wiring substrate, it becomes easy to generate gaps at the interface. If there are gaps at the interface, not only will the adhesion between the semiconductor chip and the wiring substrate decrease, but it will also hinder the heat dissipation inside the semiconductor package through the substrate.

Patent document 1 states that: a high molecular weight acrylic rubber, phenolic resin, epoxy resin, aluminum oxide filler, tetraphenylphosphonium tetraphenylborate as a curing catalyst, and a silane coupling agent are mixed in a solvent in specific amounts to prepare a varnish, and a high thermal conductivity adhesive sheet is obtained using the varnish. According to the technology described in patent document 1, by placing a silicon chip on a lead frame via the adhesive sheet, the interface thermal resistance between the adhesive layer and the lead frame can be reduced to less than 0.15K/W, and the sum of the interface thermal resistance and the internal thermal resistance of the adhesive layer (total thermal resistance) can be reduced to less than 0.55K/W.

In addition, Patent Document 2 describes a film adhesive, which contains epoxy resin (A), epoxy resin curing agent (B), phenoxy resin-containing polymer component (C), and inorganic filler material (D) whose average particle size and cumulative distribution frequency are within a specific range in specific amounts, and whose surface arithmetic average roughness Ra is less than 3.0μm, and whose thickness is within the range of more than 1μm and less than 10μm. According to the technology described in Patent Document 2, the film adhesive suppresses the generation of voids after the die attach step, improves the bonding strength with the adherend, and has excellent thermal conductivity.

[Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Publication No. 2016-219720

[Patent Document 2] Japanese Patent No. 6858315

When a film adhesive is used as a die bonding film, usually one side of the film adhesive is attached to the semiconductor wafer, and the other side is in close contact with the dicing film, with the dicing film as the base. The semiconductor wafer is singulated (diced) to produce a semiconductor chip, and the semiconductor chip and the film adhesive are peeled off (picked up) from the dicing film using the pickup collet on the die bonder. Then, the semiconductor chip is thermally pressed (bonded) to the wiring substrate to cure the film adhesive, whereby the semiconductor chip is mounted on the wiring substrate through the film adhesive. In order to fully cure the film adhesive, after the thermal pressing, the mounting substrate is exposed to a high temperature of about 180°C for about 1 hour. Recently, pressure ovens have gradually been used to perform high-temperature heating after heat pressing. The use of pressure ovens has the following advantages: the gaps between the film adhesive and the wiring board during heat pressing can be discharged over time while the curing reaction is taking place.

On the other hand, considering the damage to semiconductor packaging or energy efficiency, it is ideal for film adhesives to cure at a lower temperature range. Based on this viewpoint, the inventors have repeatedly studied the known film adhesives represented by the technology described in Patent Document 1. As a result, the following things are understood: if the heating temperature of the pressurized oven is reduced to about 120°C, the curing catalyst will not fully function and the curing reaction will become insufficient; if a curing catalyst that also functions at a lower temperature range (such as an imidazole compound) is used, the curing reaction itself will proceed, but the gaps between the film adhesive and the wiring substrate cannot be fully discharged, and gaps are likely to remain at the interface.

The present invention is made in view of the above situation, and its subject is to provide a thermally conductive film adhesive, which can make the curing reaction fully proceed under more stable conditions, and when used as a die bonding film, it can effectively suppress the gap between the adhesive and the wiring substrate in the obtained semiconductor package, so as to obtain a semiconductor package with excellent heat dissipation inside the package. In addition, the subject of the present invention is to provide a semiconductor package using the thermally conductive film adhesive and a manufacturing method thereof.

The inventors of the present invention have repeatedly conducted active research on the above-mentioned topic and found that by controlling the physical properties of the thermal conductive film adhesive containing epoxy resin (A), epoxy resin hardener (B), polymer component (C) and inorganic filler (D), the capillary rheometer viscosity under the measurement conditions of temperature 120°C and load 20Kg becomes 1~10 00Pa‧s, and the detection time of the heat peak in the differential scanning calorimetry at 120℃ becomes more than 15 minutes. Even if the film adhesive is used as a die bonding film and a heat curing reaction after the die bonding step is performed in a pressurized oven set to a relatively low temperature, the gap between the adhesive and the wiring substrate generated in the die bonding step can be efficiently discharged. Based on these insights, the inventors have completed the present invention through further repeated research.

The inventors of the present invention have repeatedly conducted active research to solve the above-mentioned problem, and found that the above-mentioned problem can be solved by the following structure.

[1]

A heat conductive film adhesive comprising an epoxy resin (A), an epoxy resin hardener (B), a polymer component (C) and an inorganic filler (D), wherein the capillary rheometer viscosity at a temperature of 120°C and a load of 20 kg is 1-1000 Pa‧s, and the detection time of the heat peak in the differential scanning calorimetry at 120°C (hereinafter referred to as "120°C DSC measurement") is more than 15 minutes.

[2]

The heat conductive film adhesive described in [1], wherein the ratio of the inorganic filler (D) to the total content of the epoxy resin (A), the epoxy resin curing agent (B), the polymer component (C) and the inorganic filler (D) is 30-70 volume %, the sphericity of the inorganic filler (D) is 0.6-1.0, and after thermal curing, a cured body having a thermal conductivity of 1.0 W/m‧K or more is provided.

[3]

The thermally conductive film adhesive described in [1] or [2] has a thickness of 1 to 20 μm.

[4]

A heat conductive film adhesive as described in any one of [1] to [3], wherein the epoxy resin curing agent (B) contains an imidazole compound.

[5]

The heat conductive film adhesive described in [4], wherein the content of the epoxy resin hardener (B) is 0.5-7 parts by mass relative to 100 parts by mass of the epoxy resin (A).

[6]

A dicing die attach film is formed by laminating a dicing die film and a thermally conductive film adhesive as described in any one of [1] to [5].

[7]

A method for manufacturing a semiconductor package, comprising: a first step of hot-pressing the heat-conductive film adhesive described in any one of [1] to [5] onto the back side of a semiconductor wafer having at least one semiconductor circuit formed on its surface, and providing a wafer-cutting film via the heat-conductive film adhesive layer; a second step of obtaining a semiconductor chip with an adhesive layer on the wafer-cutting film by integrally cutting the semiconductor wafer and the adhesive layer; a third step of removing the wafer-cutting film from the adhesive layer, and hot-pressing the semiconductor chip with the adhesive layer to a wiring board via the adhesive layer; and a fourth step of thermally curing the adhesive layer.

[8]

The method for manufacturing a semiconductor package as described in [7], wherein the first step is to heat-press the wafer-cutting adhesive film described in [6] onto the back side of the semiconductor wafer.

[9]

A method for manufacturing a semiconductor package as described in [7] or [8], wherein the thermal curing in the above-mentioned step 4 is performed in a pressurized oven set at 100-150°C.

[10]

A semiconductor package obtained by the manufacturing method described in any one of [7] to [9].

In the present invention, the numerical range represented by "~" means a range that includes the numerical values at its critical points as the lower limit and the upper limit. For example, when it is recorded as "A~B", the numerical range is "above A and below B".

In the present invention, the so-called (meth)acrylic acid means one or both of acrylic acid and methacrylic acid. The same applies to (meth)acrylate.

The thermally conductive film adhesive of the present invention can fully carry out the curing reaction under more stable conditions, and when used as a die-bonding film, it can effectively suppress the residual gap between the adhesive and the wiring substrate in the obtained semiconductor package, thereby obtaining a semiconductor package with excellent heat dissipation inside the package.

Furthermore, according to the semiconductor package manufacturing method of the present invention, the use of the thermally conductive film adhesive of the present invention as an adhesive between the semiconductor chip and the wiring substrate can effectively suppress the residual gap between the adhesive and the wiring substrate, thereby enabling the internal heat dissipation of the semiconductor package to be excellent.

Furthermore, in the semiconductor package of the present invention, the thermally conductive film adhesive of the present invention is used as the adhesive between the semiconductor chip and the wiring substrate, which suppresses the residual gap between the adhesive and the wiring substrate, and the heat dissipation inside the package is excellent.

1: Semiconductor wafer

2: Film adhesive layer

3: Cutting film

4: Semiconductor chip

5: Semiconductor chip with film adhesive layer

6: Wiring board

7:Joining line

8: Sealing resin

9:Semiconductor packaging

[Figure 1] is a schematic longitudinal cross-sectional view showing a preferred embodiment of the first step of the semiconductor package manufacturing method of the present invention.

[Figure 2] is a schematic longitudinal cross-sectional view showing a preferred embodiment of the second step of the semiconductor package manufacturing method of the present invention.

[Figure 3] is a schematic longitudinal cross-sectional view showing a preferred embodiment of the third step of the semiconductor package manufacturing method of the present invention.

[Figure 4] is a schematic longitudinal cross-sectional view showing a preferred embodiment of the bonding wire connection step of the semiconductor package manufacturing method of the present invention.

[Figure 5] is a schematic longitudinal cross-sectional view showing an example of a multi-stage lamination implementation of the semiconductor package manufacturing method of the present invention.

[Figure 6] is a schematic longitudinal cross-sectional view showing another multi-stage lamination implementation example of the semiconductor package manufacturing method of the present invention.

[Figure 7] is a schematic longitudinal cross-sectional view showing a preferred embodiment of a semiconductor package manufactured by the semiconductor package manufacturing method of the present invention.

[Thermal conductive film adhesive]

The thermally conductive film adhesive of the present invention (hereinafter, also referred to as "film adhesive") contains epoxy resin (A), epoxy resin curing agent (B), polymer component (C) and inorganic filler (D). Regarding the thermally conductive film adhesive of the present invention, the capillary rheometer viscosity of the film adhesive under the measurement conditions of temperature 120°C and load 20Kg is 1~1000Pa‧s. In addition, in the measurement performed by differential scanning calorimeter (DSC) maintained at 120°C (DSC measurement maintained at 120°C), the detection time of the heat peak is more than 15 minutes (more than 900 seconds).

In the present invention, when referring to "film", it is preferably a thin film with a thickness of less than 200μm. The shape and size when viewed from above are not particularly limited and can be adjusted appropriately according to the usage.

The film-shaped adhesive of the present invention may be composed of a film-shaped adhesive alone, or may be in a form in which a base film subjected to a demolding treatment is attached to at least one side. In addition, the film-shaped adhesive of the present invention may be in a form in which a film is cut into an appropriate size, or may be in a form in which a film is rolled into a roll.

<Capillary Rheometer Viscosity>

In the present invention, the capillary rheometer viscosity is determined in the following manner, that is, for the film adhesive before heat curing, a high-pressure flow tester is used to determine the measurement conditions of temperature 120°C and load 20Kg. Specifically, it can be determined by the method described in the following [Implementation Example] item.

The capillary rheometer viscosity of the film adhesive of the present invention is 1~1000Pa‧s, preferably 2~900Pa‧s, more preferably 5~800Pa‧s, further preferably 10~750Pa‧s, further preferably 20~700Pa‧s, further preferably 30~650Pa‧s, and further preferably 35~600Pa‧s. By making the capillary rheometer viscosity within the above range, for example, when the film adhesive of the present invention is used as a die bonding film, even if the heat curing reaction using a pressurized oven is set to a relatively low temperature, the gaps generated between the adhesive and the wiring substrate in the die bonding step can be efficiently discharged.

The viscosity of the capillary rheometer can be controlled by adjusting the type or blending amount of each raw material, adjusting the sphericity of the inorganic filler, etc.

<Detection time of the heat peak in DSC measurement at 120℃>

In the present invention, the so-called 120°C holding DSC measurement heat peak detection time refers to the heat peak detection time obtained by using a differential scanning calorimeter to raise the temperature from room temperature (25°C) to 120°C at a heating rate of 30°C/min, and then maintaining (maintaining) 120°C for 120 minutes. The detection time is the time (T3) obtained by subtracting the heat peak rise time (T1) from the heat peak end time (T2), that is, (T3=T2-T1). Specifically, it can be determined by the method described in the following [Implementation Example] item.

The film adhesive of the present invention is maintained at 120°C for a detection time of the heat peak in DSC measurement of more than 15 minutes, preferably 15 to 120 minutes, more preferably 16 to 100 minutes, further preferably 18 to 80 minutes, preferably 20 to 60 minutes, and preferably 22 to 55 minutes. By controlling the detection time of the heat peak in DSC measurement at 120°C within the above range, for example, when the film adhesive of the present invention is used as a die bonding film, even if the heat curing reaction using a pressurized oven is set to a relatively low temperature, the curing reaction can be fully carried out, and the gaps generated between the adhesive and the wiring substrate in the die bonding step can be efficiently discharged.

That is, the capillary rheometer viscosity of the film adhesive of the present invention under specific conditions and the detection time of the heat peak in the DSC measurement at 120°C are controlled within a specific range. As a result, a sufficient curing reaction under more stable conditions can be achieved, and when the film adhesive of the present invention is used as a die bonding film, even if the heat curing reaction using a pressurized oven is set to a relatively low temperature, the gaps generated between the adhesive and the wiring substrate in the die bonding step can be discharged over time and efficiently.

In the present invention or this specification, when referring to "film adhesive before heat curing", it means a heat conductive film adhesive that has not been exposed to a temperature condition of more than 25°C for more than 72 hours and has not been exposed to a temperature condition of more than 30°C after the film adhesive is manufactured.

<Thermal conductivity>

The film adhesive of the present invention preferably provides a cured body with a thermal conductivity of 1.0W/m‧K or more after thermal curing. The thermal conductivity is more preferably 1.1W/m‧K or more, further preferably 1.2W/m‧K or more, further preferably 1.5W/m‧K or more. If the thermal conductivity after thermal curing is set to 1.0W/m‧K or more, when used as a die bonding film, the heat inside the semiconductor package can be fully dissipated to the outside.

Here, the so-called "after heat curing" of the film adhesive refers to the state where the curing reaction of the film adhesive is completed. Specifically, it refers to the state where no reaction heat peak is observed when DSC measurement is performed at a heating rate of 10℃/min.

Thermal conductivity is determined by a heat flow meter method (in accordance with JIS-A1412 (2016)) using a thermal conductivity measuring device. Specifically, it can be determined by the method described in the following [Example] item.

The type or content of the inorganic filler (D) greatly contributes to setting the thermal conductivity of the film adhesive after thermal curing within the above range. In addition, the type or content of the epoxy resin (A), epoxy resin hardener (B) and polymer component (C) can also be appropriately adjusted to control the thermal conductivity.

<Epoxy resin (A)>

In the epoxy resin used in the present invention, the cross-linking density of the hardened body becomes higher, thereby increasing the contact probability of the mixed inorganic filler (D) and expanding the contact area, thereby achieving a higher filling rate. The epoxy equivalent is preferably 150~450g/eq. Furthermore, in the present invention, the so-called epoxy equivalent refers to the number of grams of resin containing 1 gram equivalent of epoxy groups (g/eq).

The mass average molecular weight of the epoxy resin (A) is usually preferably less than 10,000, and more preferably less than 5,000.

The mass average molecular weight is the value obtained by GPC (Gel Permeation Chromatography) analysis.

型、萘酚型、萘二酚型、三苯甲烷型、四苯基型、雙酚A型、雙酚F型、雙酚AD型、雙酚S型、及三羥甲基甲烷型等。其中，就獲得樹脂之結晶性低且具有良好外觀之膜狀接著劑之觀點而言，較佳為三苯甲烷型、雙酚A型、甲酚酚醛清漆型、及鄰甲酚酚醛清漆型。 Examples of the skeleton of the epoxy resin (A) include phenol novolac type, o-cresol novolac type, cresol novolac type, dicyclopentadiene type, biphenyl type, fluorene bisphenol type, trisphenol type,

The adhesives include triphenylmethane type, bisphenol A type, bisphenol F type, bisphenol AD type, bisphenol S type, and trihydroxymethylmethane type. Among them, from the viewpoint of obtaining a film-like adhesive having low crystallinity of the resin and good appearance, the preferred ones are triphenylmethane type, bisphenol A type, cresol novolac type, and o-cresol novolac type.

The content of the epoxy resin (A) in the film adhesive of the present invention is preferably 3-40% by mass, more preferably 5-35% by mass, and further preferably 7-35% by mass. By setting the content within the above preferred range, the thermal conductivity of the cured film adhesive can be further improved, and the generation of oligomer components can be suppressed so that the film state (film viscosity, etc.) is not easily changed.

<Epoxy resin hardener (B)>

As the epoxy resin hardener (B), any hardener such as amines, acid anhydrides, and polyphenols can be used. In the present invention, from the perspective of producing a film-like adhesive with low melt viscosity, which exhibits hardening properties at a high temperature exceeding a certain temperature, has fast hardening properties, and can be stored for a long time at room temperature with high storage stability, it is preferred to use a latent hardener.

As latent curing agents, for example, there can be cited: dicyandiamide compounds, imidazole compounds, curing catalyst composite polyphenol compounds, hydrazide compounds, boron trifluoride-amine complexes, amine imide compounds, polyamine salts, and their modified products or microcapsules.

When the term "~compound" is mentioned in the present invention, it means "a compound having a ~ skeleton". For example, "imidazole compound" means, in addition to imidazole itself, a form in which at least a portion of the hydrogen atoms of imidazole are substituted.

As the epoxy resin hardener (B), one of the above hardeners may be used alone, or two or more may be used in combination. From the perspective of having better latency (excellent stability at room temperature and the property of being hardenable by heating) and faster curing speed, it is preferred that the epoxy resin hardener (B) contains an imidazole compound, and it is more preferred that the epoxy resin hardener (B) is an imidazole compound.

In the film adhesive of the present invention, the content of the epoxy resin hardener (B) is preferably 0.5 to 100 parts by mass, and more preferably 1 to 80 parts by mass, relative to 100 parts by mass of the epoxy resin (A). By setting the content to be above the above-mentioned preferred lower limit, the curing time can be shortened. On the other hand, by setting the content to be below the above-mentioned preferred upper limit, the defects in the reliability test after the film adhesive is assembled in the semiconductor due to "excess hardener remaining in the film adhesive and the residual hardener absorbing moisture" can be reduced.

Furthermore, when the epoxy resin hardener (B) contains an imidazole compound, in the film adhesive, the content of the epoxy resin hardener (B) is preferably 0.5 to 7 parts by mass, more preferably 1 to 6 parts by mass, further preferably 1.2 to 5.5 parts by mass, further preferably 1.4 to 5 parts by mass, further preferably 1.5 to 4 parts by mass, relative to 100 parts by mass of the epoxy resin (A). In this case, it is preferred that the epoxy resin hardener (B) is an imidazole compound.

<Polymer component (C)>

The polymer component (C) may be any component that suppresses the film viscosity at room temperature (25°C) when forming a film-like adhesive (the property that the film state is easily changed even with a slight temperature change) and imparts sufficient adhesion and film-forming properties. Examples of the polymer component (C) include natural rubber, butyl rubber, isoprene rubber, chloroprene rubber, ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylate copolymer, polybutadiene resin, polycarbonate resin, thermoplastic polyimide resin, polyamide resins such as 6-nylon and 6,6-nylon; phenoxy resin, (meth)acrylic resin, polyester resins such as polyethylene terephthalate and polybutylene terephthalate; polyamide imide resin; and fluororesin, etc.

These polymer components (C) can be used alone or in combination of two or more.

The mass average molecular weight of the polymer component (C) is 10,000 or more. The upper limit is not particularly limited, but 5,000,000 or less is more practical, preferably 700,000 or less, and preferably 600,000 or less.

The mass average molecular weight of the polymer component (C) is a value obtained by GPC (Gel Permeation Chromatography) in terms of polystyrene. The following specific mass average molecular weight values of the polymer component (C) also have the same meaning.

In addition, the glass transition temperature (Tg) of the polymer component (C) is preferably less than 100°C, and more preferably less than 90°C. The lower limit is preferably above 0°C, and more preferably above 10°C.

The glass transition temperature of the polymer component (C) is the glass transition temperature measured by DSC at a heating rate of 0.1°C/min. The values of the specific glass transition temperatures of the polymer component (C) below also have the same meaning.

In the present invention, for epoxy resins (A) and phenoxy resins in polymer components (C) that may have epoxy groups, resins with epoxy equivalents of 500 g/eq or less are classified as epoxy resins (A), and those that do not meet the requirements are classified as polymer components (C).

In the present invention, it is preferred to use at least one phenoxy resin among the polymer components (C). Phenoxy resins have similar structures to epoxy resins (A), so they can exhibit good compatibility, low resin melt viscosity, and excellent adhesion. In addition, phenoxy resins are also preferred from the perspective of high heat resistance, low saturated water absorption, and ensuring the reliability of semiconductor packaging. Furthermore, phenoxy resins are also preferred in terms of eliminating stickiness and brittleness at room temperature.

Phenoxy resins can be obtained by the reaction of bisphenol or diphenol compounds with epihalohydrin such as epichlorohydrin, or by the reaction of liquid epoxy resins with bisphenol or diphenol compounds.

In any reaction, the bisphenol or biphenol compound is preferably a compound represented by the following general formula (A).

In the general formula (A), ^La represents a single bond or a divalent linking group, ^Ra1 and ^Ra2 each independently represent a substituent, and ma and na each independently represent an integer of 0 to 4.

In L ^a , the divalent linking group is preferably an alkylene group, a phenylene group, -O-, -S-, -SO-, -SO ₂ -, or a group consisting of an alkylene group and a phenylene group.

The carbon number of the alkylene group is preferably 1 to 10, more preferably 1 to 6, further preferably 1 to 3, particularly preferably 1 or 2, and most preferably 1.

The alkylene group is preferably -C(R ^α )(R ^β )-, wherein R ^α and R ^β each independently represent a hydrogen atom, an alkyl group, or an aryl group. R ^α and R ^β may be bonded to each other to form a ring. ^{R α} and R ^β are preferably a hydrogen atom or an alkyl group (e.g., methyl, ethyl, isopropyl, n-propyl, n-butyl, isobutyl, hexyl, octyl, 2-ethylhexyl). Among them, the alkylene group is preferably -CH ₂ -, -CH(CH ₃ )-, or -C(CH ₃ ) ₂ -, more preferably -CH ₂ - or -CH(CH ₃ )-, and further preferably -CH ₂ -.

The carbon number of the phenyl group is preferably 6 to 12, more preferably 6 to 8, and even more preferably 6. Examples of the phenyl group include p-phenyl, m-phenyl, and o-phenyl, with p-phenyl and m-phenyl being preferred.

The group formed by combining an alkylene group and a phenylene group is preferably an alkylene-phenylene-alkylene group, and more preferably -C(R ^α )(R ^β )-phenylene-C(R ^α )(R ^β )-.

The ring formed by the bonding of R ^α and R ^β is preferably a five- or six-membered ring, more preferably a cyclopentane ring or a cyclohexane ring, and still more preferably a cyclohexane ring.

^{La is} preferably a single bond, an alkylene group, -O-, or _-SO2- , and more preferably an alkylene group.

In R ^a1 and R ^a2 , the substituent is preferably an alkyl group, an aryl group, an alkoxy group, an alkylthio group, or a halogen atom, more preferably an alkyl group, an aryl group, or a halogen atom, and still more preferably an alkyl group.

Ma and Na are preferably 0 to 2, more preferably 0 or 1, and even more preferably 0.

Examples of bisphenol or biphenol compounds include: bisphenol A, bisphenol AD, bisphenol AP, bisphenol AF, bisphenol B, bisphenol BP, bisphenol C, bisphenol E, bisphenol F, bisphenol G, bisphenol M, bisphenol S, bisphenol P, bisphenol PH, bisphenol TMC and bisphenol Z; and 4,4'-biphenol, 2,2'-dimethyl-4,4'-biphenol, 2,2',6,6'-tetramethyl-4,4'-biphenol and Cardo skeleton type bisphenol, etc.; among them, bisphenol A, bisphenol AD, bisphenol C, bisphenol E, bisphenol F and 4,4'-biphenol are preferred, bisphenol A, bisphenol E and bisphenol F are more preferred, and bisphenol A is particularly preferred.

On the other hand, as the liquid epoxy resin, the diglycidyl ether of the aliphatic diol compound is preferred, and the compound represented by the following general formula (B) is more preferred.

In the general formula (B), X represents an alkylene group, and nb represents an integer from 1 to 10.

The carbon number of the alkylene group is preferably 2 to 10, more preferably 2 to 8, further preferably 3 to 8, particularly preferably 4 to 6, and most preferably 6.

For example, ethyl, propyl, butyl, pentyl, hexyl, and octyl can be cited, and ethyl, trimethylene, tetramethylene, pentamethylene, heptamethylene, heptamethylene, and octamethylene are preferred.

The best nb is 1~6, more preferably 1~3, and even better 1.

Here, when nb is 2 to 10, X is preferably an ethyl group or a propyl group, and more preferably an ethyl group.

Examples of the aliphatic diol compound in diglycidyl ether include ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, and 1,8-octanediol.

In the above reaction, the bisphenol or biphenol compound or the aliphatic diol compound may be a phenoxy resin obtained by reacting alone, or may be a phenoxy resin obtained by reacting two or more of them together. For example, the reaction of diglycidyl ether of 1,6-hexanediol with a mixture of bisphenol A and bisphenol F can be cited.

The phenoxy resin in the present invention is preferably a phenoxy resin obtained by reacting a liquid epoxy resin with a bisphenol or biphenol compound, and more preferably a phenoxy resin having a repeating unit represented by the following general formula (I).

In the general formula (I), ^La , ^Ra1 , ^Ra2 , ma and na have the same meanings as ^La , ^Ra1 , ^Ra2 , ma and na in the general formula (A), and their preferred ranges are also the same. X and nb have the same meanings as X and nb in the general formula (B), and their preferred ranges are also the same.

In the present invention, the preferred polymer is bisphenol A and diglycidyl ether of 1,6-hexanediol.

The mass average molecular weight of the phenoxy resin is preferably above 10,000, more preferably 10,000 to 100,000.

In addition, the amount of trace epoxy groups remaining in the phenoxy resin is preferably 5000 g/eq or more in terms of epoxy equivalent.

The glass transition temperature (Tg) of the phenoxy resin is preferably less than 100°C, more preferably less than 90°C. The lower limit is preferably above 0°C, more preferably above 10°C.

Phenoxy resins can be synthesized by the method described above, and commercial products can also be used. Examples of commercial products include: YX7180 (trade name: bisphenol F + 1,6-hexanediol diglycidyl ether type phenoxy resin, manufactured by Mitsubishi Chemical Corporation), 1256 (trade name: bisphenol A type phenoxy resin, manufactured by Mitsubishi Chemical Corporation), YP-50 (trade name: bisphenol A type phenoxy resin, manufactured by NSCC Epoxy Manufacturing), YP-70 (trade name: bisphenol A/F type phenoxy resin, manufactured by NSCC Epoxy Manufacturing), FX-316 (trade name: bisphenol F type phenoxy resin, manufactured by NSCC Epoxy Manufacturing), FX-280S (trade name: Cardo skeleton type phenoxy resin, manufactured by NSCC Epoxy Manufacturing Company), and 4250 (trade name: bisphenol A type/F type phenoxy resin, manufactured by Mitsubishi Chemical Company), etc.

As the (meth)acrylic resin, a resin composed of a general (meth)acrylic acid copolymer is used.

The mass average molecular weight of the (meth)acrylic acid copolymer is preferably 10,000 to 2,000,000, and more preferably 100,000 to 1,500,000. By setting the mass average molecular weight within the above preferred range, the viscosity can be reduced and the increase in melt viscosity can be suppressed.

The glass transition temperature of the (meth)acrylic acid copolymer is preferably in the range of -10 to 50°C, more preferably in the range of 0 to 40°C, and further preferably in the range of 0 to 30°C. By setting the glass transition temperature within the above preferred range, the viscosity can be reduced and the generation of gaps between the semiconductor wafer and the film adhesive can be suppressed.

As the above-mentioned (meth) acrylic resin, there can be cited poly (meth) acrylic acid esters or their derivatives. For example, there can be cited copolymers having 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, acrylic acid, methacrylic acid, itaconic acid, glycidyl methacrylate, glycidyl acrylate, etc. as monomer components.

In addition, the following substances can also be used as monomer components: (meth)acrylates having a cyclic skeleton, such as cycloalkyl (meth)acrylate, benzyl (meth)acrylate, isoborneol (meth)acrylate, dicyclopentyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, and imido (meth)acrylate; and (meth)acrylate alkyl esters having an alkyl group with a carbon number of 1 to 18, such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and butyl (meth)acrylate.

Furthermore, it can also be copolymerized with vinyl acetate, (meth)acrylonitrile, or styrene. In addition, those with hydroxyl groups are preferred because they have good compatibility with epoxy resins.

The content of the polymer component (C) is preferably 1 to 40 parts by mass, more preferably 5 to 35 parts by mass, and further preferably 10 to 30 parts by mass relative to 100 parts by mass of the epoxy resin (A). By setting the content within this range, the rigidity and flexibility of the thermal conductive film adhesive before curing can be adjusted. In addition, the film state becomes better (the film viscosity is reduced), and the film fragility can also be suppressed.

<Inorganic filler (D)>

The inorganic filler material (D) may be any inorganic filler material that can be used for die-bonding films without particular limitation.

Examples of the inorganic filler (D) include: ceramics such as silicon dioxide, clay, gypsum, calcium carbonate, barium sulfate, aluminum oxide, ceria, magnesium oxide, silicon carbide, silicon nitride, aluminum nitride, and boron nitride; metals or alloys such as aluminum, copper, silver, gold, nickel, chromium, tin, zinc, palladium, and solder; and carbons such as carbon nanotubes and graphene; and various inorganic powders.

The average particle size (d50) of the inorganic filler (D) is not particularly limited. From the perspective of suppressing the formation of treatment marks and improving the adhesion, it is preferably 0.01~10.0μm, more preferably 0.1~7.0μm, and further preferably 0.3~6.0μm. The average particle size (d50) is the so-called median particle size, which means the particle size at which the total volume of the particles is set to 100% in the cumulative distribution when the particle size distribution is measured by the laser diffraction scattering method.

The true sphericity of the inorganic filler (D) can be appropriately set to control the capillary rheometer viscosity of the film adhesive as the target. For example, if the true sphericity is set to 0.6~1.0, the capillary rheometer viscosity of the film adhesive can be suppressed even if a large amount of inorganic filler is mixed to a certain extent. From this point of view, the true sphericity of the inorganic filler (D) is preferably 0.65~0.99, more preferably 0.80~0.99, and also preferably 0.90~0.99. The true sphericity is determined by observing the inorganic filler (D) using a scanning electron microscope and based on its area and circumference. Specifically, it can be determined by referring to the measurement method described in the following [Example].

The Mohs hardness of the inorganic filler material is not particularly limited. From the perspective of suppressing the generation of jig marks and improving the crystal adhesion, it is preferably 2 or more, and more preferably 2 to 9. The Mohs hardness can be measured by a Mohs hardness tester.

The inorganic filler (D) is preferably an inorganic filler having a thermal conductivity of 12W/m‧K or more. The inorganic filler having a thermal conductivity of 12W/m‧K or more is a particle composed of a thermally conductive material or a particle whose surface is coated with the thermally conductive material. The thermal conductivity of the thermally conductive material is preferably 12W/m‧K or more, and more preferably 30W/m‧K or more.

If the thermal conductivity of the thermally conductive material is above the above-mentioned preferred lower limit, the amount of inorganic filler (D) mixed to obtain the target thermal conductivity can be reduced, resulting in the ability to suppress the increase in the melt viscosity of the bonding film, improve the embedding property into the concave and convex parts of the substrate when pressed onto the substrate, and suppress the generation of voids.

In the present invention, the thermal conductivity of the thermal conductive material refers to the thermal conductivity at 25°C, and the literature value of each material can be used. Even if there is no record in the literature, for example, if it is ceramic, the value measured according to JIS R 1611 (2010) can be used instead, and if it is metal, the value measured according to JIS H 7801 (2005) can be used instead.

As inorganic filler (D), for example, thermally conductive ceramics can be cited, preferably: aluminum oxide particles (thermal conductivity: 36W/m.K), aluminum nitride particles (thermal conductivity: 150~290W/m.K), boron nitride particles (thermal conductivity: 60W/m.K), zinc oxide particles (thermal conductivity: 54W/m.K), silicon nitride filler (thermal conductivity: 27W/m.K), silicon carbide particles (thermal conductivity: 200W/m.K) and magnesium oxide particles (thermal conductivity: 59W/m.K).

In particular, aluminum oxide particles have high thermal conductivity and are better in terms of dispersibility and availability. In addition, aluminum nitride particles or boron nitride particles are better from the perspective of having higher thermal conductivity than aluminum oxide particles. In the present invention, aluminum oxide particles and aluminum nitride particles are preferred.

In addition, metal particles with higher thermal conductivity than ceramics, or particles with metal coating on the surface can also be cited. For example, single metal fillers such as silver (thermal conductivity: 429W/m.K), nickel (thermal conductivity: 91W/m.K) and gold (thermal conductivity: 329W/m.K), or polymer particles such as acrylic resin or polysilicone resin with such metal coating on the surface can be preferably cited.

In the present invention, from the perspective of high thermal conductivity and resistance to oxidative degradation, gold or silver particles are more preferred.

The inorganic filler (D) may be surface treated or surface modified. Examples of such surface treatment or surface modification include silane coupling agents, phosphoric acid or phosphoric acid compounds, and surfactants. In addition to the items described in this specification, for example, the silane coupling agents, phosphoric acid or phosphoric acid compounds, and surfactants described in the thermal conductive filler item in International Publication No. 2018/203527 or the aluminum nitride filler item in International Publication No. 2017/158994 may also be applied.

As a method for blending the inorganic filler (D) into resin components such as epoxy resin (A), epoxy resin hardener (B) and polymer component (C), the following methods can be used: a method of directly blending a powdered inorganic filler and, as required, a silane coupling agent, phosphoric acid or a phosphoric acid compound or a surfactant (integral blending); or a method of dispersing an inorganic filler treated with a surface treatment agent such as a silane coupling agent, phosphoric acid or a phosphoric acid compound or a surfactant in an organic solvent and blending the resulting slurry-like inorganic filler.

Furthermore, the method of treating the inorganic filler (D) with a silane coupling agent is not particularly limited, and examples thereof include: a wet method of mixing the inorganic filler (D) and the silane coupling agent in a solvent; a dry method of treating the inorganic filler (D) and the silane coupling agent in a gas phase; and the above-mentioned overall mixing method, etc.

In particular, although aluminum nitride particles contribute to high heat conductivity, they are prone to generate ammonium ions due to hydrolysis, so it is better to use them together with phenolic resins with low moisture absorption rate, or inhibit hydrolysis by surface modification. As a surface modification method for aluminum nitride, the following method is particularly preferred: providing an aluminum oxide layer on the surface layer to improve water resistance, and using phosphoric acid or phosphoric acid compounds for surface treatment to improve affinity with the resin.

Silane coupling agents are those with at least one hydrolyzable group such as alkoxy or aryloxy bonded to the silicon atom. In addition, alkyl, alkenyl, and aryl groups may also be bonded. The alkyl group is preferably substituted by an amino group, an alkoxy group, an epoxy group, or a (meth)acryloyloxy group, and more preferably substituted by an amino group (preferably a phenylamino group), an alkoxy group (preferably a glycidoxy group), or a (meth)acryloyloxy group.

Examples of the silane coupling agent include 2-(3,4-epoxyhexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, methyltrimethoxysilane, Oxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, 3-methacryloyloxypropylmethyldimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropylmethyldiethoxysilane, 3-methacryloyloxypropyltriethoxysilane, etc.

The silane coupling agent or surfactant is preferably contained in an amount of 0.1 to 2.0 parts by mass relative to 100 parts by mass of the inorganic filler (D).

By setting the content of the silane coupling agent or surfactant within the above preferred range, the aggregation of the inorganic filler (D) can be suppressed, and the peeling at the bonding interface caused by the volatilization of the excess silane coupling agent or surfactant in the semiconductor assembly heating step (such as the reflow step) can be suppressed, the generation of voids can be suppressed, and the adhesion can be improved.

The shape of the inorganic filler (D) is not particularly limited, and examples thereof include: flake, needle, filament, spherical, or scale-shaped. From the perspective of high filling and fluidity, spherical particles are preferred.

In the present invention, the ratio of the inorganic filler (D) in the total content of the epoxy resin (A), the epoxy resin hardener (B), the polymer component (C) and the inorganic filler (D) is preferably 30-70 volume %. By setting the content of the inorganic filler (D) within the above range, it is easy to give the film adhesive the required thermal conductivity and melt viscosity, which can fully demonstrate the effect of heat dissipation from the semiconductor package, and can also prevent the overflow of the film adhesive, and further suppress the generation of voids in the die bonding step. In addition, it can also improve the effect of relieving the internal stress generated by the semiconductor package during thermal changes, which is also helpful to improve the bonding strength.

The ratio of the above-mentioned inorganic filler (D) to the total content of components (A) to (D) is preferably 30 to 60 volume %, and more preferably 30 to 50 volume %.

The content (volume %) of the above-mentioned inorganic filler (D) can be calculated based on the mass and specific gravity of each component (A) to (D).

<Other ingredients>

The film adhesive of the present invention contains not only the above-mentioned epoxy resin (A), the above-mentioned epoxy resin hardener (B), the above-mentioned polymer component (C), and the above-mentioned inorganic filler (D), but also additives such as organic solvents (MEK (Methyl ethyl ketone) etc.), ion trapping agents (ion trapping agents), viscosity modifiers, antioxidants, flame retardants, colorants, butadiene rubber or polysilicone rubber and other stress relievers within the scope that does not damage the effect of the present invention. For example, the description of other additives in International Publication No. 2017/158994 can be applied.

The total content of the epoxy resin (A), the epoxy resin hardener (B), the polymer component (C) and the inorganic filler (D) in the film adhesive of the present invention is not particularly limited as long as the film adhesive of the present invention can be obtained. For example, it can be set to 60~95% by mass, preferably 70~90% by mass.

[Manufacturing method of film adhesive]

As a preferred embodiment of the method for producing the film-like adhesive of the present invention, the following method can be cited: generally, the components of the film-like adhesive are uniformly mixed in a solvent to prepare a composition (film-like adhesive forming composition), the composition is applied to one side of a substrate film that has been subjected to a demolding treatment, and the solvent is removed by heating and drying.

As the base film after mold release treatment, as long as it functions as a covering film of the obtained film-like adhesive, a common one can be appropriately adopted. For example, polypropylene (PP) after mold release treatment, polyethylene (PE) after mold release treatment, and polyethylene terephthalate (PET) after mold release treatment can be exemplified. As the coating method, a common method can be appropriately adopted, for example, a roll knife coater, a gravure coater, a die coater, or a reverse coater can be exemplified.

The thickness of the film adhesive of the present invention obtained in this way is preferably 1-200μm, more preferably 1-100μm, further preferably 1-50μm, preferably 1-30μm, and preferably 1-20μm. The above thickness is also preferably set to 2μm or more, and preferably set to 3μm or more. By controlling the thickness of the film adhesive in the above manner, for example, when used as a die bonding film, it can be more fully embedded in the uneven parts of the wiring substrate or semiconductor chip surface and the thermal conductivity is also excellent. In addition, the organic solvent can be fully removed during manufacturing, and it can be made into a form that exhibits appropriate film viscosity.

The thickness of film adhesive can be measured by contact linear gauge (desktop contact thickness measuring device).

The film adhesive of the present invention preferably has an arithmetic average roughness Ra of at least one surface (i.e., at least one side in contact with the adherend) of 3.0 μm or less, and preferably has an arithmetic average roughness Ra of both sides of 3.0 μm or less.

The above arithmetic mean roughness Ra is preferably less than 2.0μm, and more preferably less than 1.5μm. The lower limit is not particularly limited, and 0.1μm or more is more practical.

[Crystal cutting and bonding film]

The film-like adhesive of the present invention is suitable as a die bonding film used in the semiconductor manufacturing step. Therefore, a dicing die bonding film (dicing die bond film) can be formed by laminating a dicing film with the film-like adhesive of the present invention.

For example, a coating liquid containing an adhesive is applied to a release-treated peeling pad and dried to form a wafer film, and the wafer film is laminated to a base film to obtain a laminate having a base film, a wafer film, and a peeling pad laminated in sequence. Alternatively, a wafer bonding film forming composition (the above-mentioned film-like adhesive forming composition) is applied to a peeling film (which has the same meaning as the peeling pad, and the description is changed here for convenience) and dried to form a wafer bonding film on the peeling film. Then, the cut wafer film and the die bonding film are bonded together by connecting the cut wafer film exposed after peeling off the peeling pad, thereby obtaining a cut wafer bonding film having a base film, a cut wafer film, a die bonding film, and a peeling film sequentially stacked thereon.

The bonding of the above-mentioned wafer cutting film and wafer bonding film is preferably performed under pressure.

As the adhesive constituting the cut crystal film, the general adhesive used in the cut crystal film application, such as acrylic adhesive, rubber adhesive, etc., can be appropriately used. Among them, it is preferred that the cut crystal film is energy ray curable. As for the composition of the cut crystal film, for example, reference can be made to Japanese Patent Publication No. 2010-232422, Japanese Patent Publication No. 2661950, Japanese Patent Publication No. 2002-226796, Japanese Patent Publication No. 2005-303275, etc.

In the bonding of the above-mentioned wafer cutting film and the wafer bonding film, the shape of the wafer cutting film is not particularly limited as long as it can cover the opening of the ring frame, and is preferably circular, and the shape of the wafer bonding film is not particularly limited as long as it can cover the back of the wafer, and is preferably circular. The wafer cutting film is preferably larger than the wafer bonding film, and its shape has a portion where the adhesive layer is exposed around the adhesive layer. In this way, it is preferred to bond the wafer cutting film cut into the desired shape to the wafer bonding film.

The wafer-cutting adhesive film made in the above manner is used after the peeling film is peeled off.

[Semiconductor package and its manufacturing method]

Next, the preferred embodiment of the semiconductor package and the manufacturing method thereof of the present invention is described in detail with reference to the drawings. Furthermore, in the following description and drawings, the same symbols are used to mark the same or equivalent components, and repeated descriptions are omitted. Figures 1 to 7 are schematic longitudinal cross-sectional views of the preferred embodiment of each step of the manufacturing method of the semiconductor package of the present invention.

In the manufacturing method of the semiconductor package of the present invention, first, as the first step, as shown in FIG. 1, the film-like adhesive of the present invention is heat-pressed on the back side of the semiconductor wafer 1 having at least one semiconductor circuit formed on the surface (i.e., the surface of the semiconductor wafer 1 without a semiconductor circuit formed thereon) to provide an adhesive layer 2, and then, the semiconductor wafer 1 and the wafer-cutting film 3 are provided through the adhesive layer 2. At this time, the laminated body in which the adhesive layer 2 and the wafer-cutting film 3 are integrated can be heat-pressed once. The conditions for heat-pressing are not particularly limited as long as the epoxy resin (A) is heat-cured and the effect of the present invention is not damaged. For example, the conditions of 70°C and a pressure of 0.3MPa can be cited.

As the semiconductor wafer 1, a semiconductor wafer having at least one semiconductor circuit formed on the surface can be appropriately used, such as a silicon wafer, a SiC wafer, and a GaN wafer. As the adhesive layer 2, a single layer of the thermally conductive film adhesive of the present invention can be used, or two or more layers can be laminated for use. As a method for setting such an adhesive layer 2 on the back side of the wafer 1, a method that can deposit the above-mentioned film adhesive on the back side of the semiconductor wafer 1 can be appropriately adopted, and the following methods can be cited as examples: after laminating the above-mentioned film adhesive on the back side of the semiconductor wafer 1, in the case of laminating more than 2 layers, the film adhesive is sequentially deposited until the required thickness is reached; or a method of laminating the film adhesive to the target thickness in advance and then laminating it on the back side of the semiconductor wafer 1. In addition, as a device used when setting such an adhesive layer 2 on the back side of the semiconductor wafer 1, there is no particular limitation, for example, a common device such as a roll laminator or a manual laminator can be appropriately used.

Next, as the second step, as shown in FIG. 2 , by integrally cutting the semiconductor wafer 1 and the adhesive layer 2, a semiconductor chip 5 having an adhesive layer attached to the semiconductor wafer 1 and the adhesive layer 2 on the cut film 3 is obtained. The cut film 3 is not particularly limited, and a common cut film can be used. Furthermore, the device used for cutting is also not particularly limited, and a common cutting device can be used.

Next, as the third step, as shown in FIG. 3 , the wafer cut film 3 is removed from the adhesive layer 2, and the semiconductor chip 5 with the adhesive layer attached is heat-pressed with the wiring substrate 6 via the adhesive layer 2, and the semiconductor chip 5 with the adhesive layer attached is mounted on the wiring substrate 6 (chip bonding step). As the wiring substrate 6, it can be appropriately used for a substrate having a semiconductor circuit formed on the surface, such as a printed circuit substrate (PCB), various lead frames, and a substrate having electronic components such as resistors or capacitors mounted on the surface of the substrate.

There is no particular limitation on the method of mounting the semiconductor chip 5 with the adhesive layer on the wiring substrate 6. The usual method of "bonding the semiconductor chip 5 with the adhesive layer to the wiring substrate 6 or the electronic components mounted on the surface of the wiring substrate 6 by using the adhesive layer 2" can be appropriately adopted. As such mounting methods, the following usual heating and pressurizing methods can be cited as examples: a method using "mounting technology using a flip chip bonding machine with a function of heating from the top"; a method using a die bonding machine with a function of heating only from the bottom; a method using a bonding machine.

In this way, by mounting the semiconductor chip 5 with the adhesive layer attached on the wiring substrate 6 via the adhesive layer 2 composed of the film-like adhesive of the present invention, the film-like adhesive can be made to match the concave and convex parts on the wiring substrate 5 caused by the electronic components, so that the semiconductor chip 4 can be closely attached to the wiring substrate 6 and fixed.

Next, as the fourth step, the film adhesive of the present invention is thermally cured. The thermal curing temperature is not particularly limited as long as it is at least the thermal curing starting temperature of the film adhesive of the present invention. It varies depending on the types of epoxy resin (A), polymer component (C) and epoxy resin curing agent (B) used and cannot be generalized. However, considering the damage to semiconductor packaging or energy efficiency, the film adhesive is preferably cured in a lower temperature range (e.g., 100-150°C). If the heating temperature of the pressurized oven is set within the above low temperature range, there is a possibility that the curing catalyst will not fully function and the curing reaction will become insufficient. Therefore, it is better to use a hardener that can fully perform the hardening reaction even in this low temperature range. If such a hardener is used, the hardening reaction will proceed quickly, thus shortening the time until the hardening is completed. In this case, the inventors have found that when a specific hardening catalyst is used in a specific amount, the hardening reaction rate can be appropriately suppressed, while the hardening reaction can be fully performed in the above-mentioned low temperature range. By using this hardening reaction characteristic, a pressurized oven in a relatively low temperature range of about 100~150℃ can be used for thermal hardening reaction, while the gaps generated between the adhesive layer 2 and the wiring substrate 6 in the die bonding step can be discharged over time and fully.

Next, in the manufacturing method of the semiconductor package of the present invention, as shown in FIG4 , it is preferable to connect the wiring substrate 6 and the semiconductor chip 5 with the adhesive layer attached via the bonding wire 7. There is no particular limitation on the connection method, and a common method such as a wire bonding method and a TAB (Tape Automated Bonding) method can be appropriately adopted.

In addition, another semiconductor chip 4 can be heat-pressed onto the surface of the loaded semiconductor chip 4, heat-cured, and connected to the wiring substrate 6 again by wire bonding, thereby laminating multiple layers. For example, there are the following methods: as shown in Figure 5, a method of staggering semiconductor chips for lamination; or as shown in Figure 6, a method of embedding bonding wires 7 while laminating by thickening the adhesive layer 2 after the second layer, etc.

In the manufacturing method of the semiconductor package of the present invention, it is preferred that as shown in FIG. 7, the wiring substrate 6 and the semiconductor chip 5 with the adhesive layer attached are sealed by a sealing resin 8, so that a semiconductor package 9 can be obtained. There is no particular restriction on the sealing resin 8, and a common sealing resin that can be used to manufacture semiconductor packages can be used. In addition, there is no particular restriction on the method of sealing using the sealing resin 8, and a common method can be used.

By using the semiconductor package manufacturing method of the present invention, even in the form of a thin film, it is possible to suppress the generation of voids after the die bonding step, and to provide an adhesive layer 2 that can exhibit a high bonding strength with the adherend. In addition, by exhibiting excellent thermal conductivity after thermal curing, the heat generated on the surface of the semiconductor chip 4 can be efficiently dissipated to the outside of the semiconductor package 9.

[Implementation example]

The present invention is described in more detail below based on embodiments and comparative examples, but the present invention is not limited to the following embodiments.

In each embodiment and comparative example, room temperature refers to 25°C, MEK is methyl ethyl ketone, and PET is polyethylene terephthalate.

[Measurement, analysis]

<True sphericity of inorganic filler materials>

A small amount of various inorganic fillers were placed on a glass substrate and observed using a scanning electron microscope (Model: FlexSEM 1000II, manufactured by Hitachi Advanced Technologies Co., Ltd.) at a magnification of 10,000. Based on the observed image, the area and perimeter of each inorganic filler were measured using particle analysis software, and the concavity and convexity of each inorganic filler was calculated using the following formulas (1) and (2).

The unevenness of the inorganic filler material = (perimeter ² × area) × 1/4π (1)

The true sphericity of the inorganic filler material = 1/the concavity and convexity of the inorganic filler material (2)

Randomly observe 10 inorganic filler materials in the observed image, and take the arithmetic average of the true sphericity of the 10 inorganic filler materials as the true sphericity of the inorganic filler material blended in the film adhesive.

<Determination of viscosity using a capillary rheometer>

10g of the thermal conductive film adhesive obtained in each embodiment and comparative example was cut and processed into a cylindrical shape of 25mm high and 10mm in diameter using a simple press. The processed sample was placed in a cylinder of a high-pressure flow tester (CFT-500EX) manufactured by Shimadzu Corporation heated to 120°C and left for 20 seconds. Then, the capillary rheometer viscosity was measured under the measurement conditions of temperature 120°C and load 20kg (with a 1.5kg lead).

<Detection time of the heat peak in DSC measurement at 120℃>

10 mg of the thermally conductive film adhesive obtained in each embodiment and comparative example was cut and measured using a differential scanning calorimeter (model: DSC7000, manufactured by Hitachi High-Tech Science Co., Ltd.) with a heating rate of 30°C/min from room temperature (25°C) to 120°C, and then maintained at 120°C for 120 minutes. Based on the obtained heat peak, the heat peak rise time T1 and heat peak end time T2 were determined using thermal analysis software (software name: SOFTWARE FOR NEXTA), and the heat peak detection time T3 was calculated.

T3=T2-T1

T1: The time of the intersection of the tangent line of the rising part of the heating peak and the baseline

T2: The time of the intersection of the tangent line of the descending part of the fever peak and the baseline

<Evaluation of gap after hardening>

First, a manual laminating machine (trade name: FM-114, manufactured by TECHNOVISION) was used to laminate the thermally conductive film adhesive obtained in each embodiment and comparative example onto one surface of a dummy silicon wafer (size 8 inches, thickness 100 μm) at a temperature of 70°C and a pressure of 0.3 MPa. The peeling film of the heat conductive film adhesive on the opposite side to the above-mentioned dummy silicon wafer is peeled off, and a wafer cutting film (trade name: K-13, manufactured by Furukawa Electric Industries, Ltd.) and a dicing frame (trade name: DTF2-8-1H001, manufactured by DISCO Corporation) are laminated on the surface of the heat conductive film adhesive on the opposite side to the above-mentioned dummy silicon wafer using the same manual laminating machine at room temperature (25°C) and a pressure of 0.3MPa. Next, a dicing device (trade name: DFD-6340, manufactured by DISCO) equipped with a double-axis dicing blade (Z1: NBC-ZH2050 (27HEDD), manufactured by DISCO / Z2: NBC-ZH127F-SE (BC), manufactured by DISCO) was used to cut the dummy silicon wafer from the side to make it a square with a size of 10 mm × 10 mm, and a dummy wafer with an adhesive layer attached was obtained.

Next, ultraviolet rays were irradiated from the back side of the wafer using an ultraviolet irradiation device (trade name: RAD-2000F/8, manufactured by LINTEC, irradiation dose 200mJ/ ^cm2 ), and the dummy wafer with the adhesive layer was heat-pressed onto the mounting surface side of an organic substrate with uneven surface (BT resin system, surface unevenness Rz value 5μm, manufactured by KYODEN) using a die bonder (trade name: DB-800, manufactured by Hitachi Advanced Technologies) under the following pick-up conditions and die bonding conditions. Thereafter, the adhesive layer of the dummy wafer with the adhesive layer heat-pressed onto the substrate was heat-cured using a press oven (trade name: VTS-60A, manufactured by APT) under the following press curing conditions. The presence of voids at the interface between the adhesive layer and the mounting surface of the organic substrate was observed using an ultrasonic flaw detector (SAT) (model: FS300III, manufactured by Hitachi Power Solutions) and the adhesion was evaluated based on the following evaluation criteria.

-Pickup conditions-

Number of needles: 5 (350R), needle height: 200μm, pickup timer: 100msec

-Die bonding conditions-

120℃, pressure 0.1MPa (load 400gf), time 1.0 second

-Pressure hardening conditions-

120℃, pressure 7.0f/ ^cm2 , time 30 minutes, 60 minutes, or 90 minutes

-Evaluation Criteria-

AAA: No voids were observed in all 24 dummy chips mounted with a press cure time of 30 minutes.

AA: Does not meet AAA above, but no voids were observed in all 24 dummy chips mounted with a press cure time of 60 minutes.

A: Does not meet AAA and AA above, but no voids were observed in all 24 dummy chips mounted with a press curing time of 90 minutes.

B: Among the 24 dummy chips installed with a pressurized curing time of 90 minutes, 1 to 5 chips had gaps.

C: Among the 24 dummy chips installed with a press hardening time of 90 minutes, more than 6 chips had gaps.

<Thermal conductivity>

Cut a square piece with a side of more than 50mm from the manufactured thermal conductive film adhesive, and overlap the cut samples to obtain an adhesive layer with a thickness of more than 5mm.

The sample was placed on a disc-shaped mold with a diameter of 50mm and a thickness of 5mm, and heated for 10 minutes at a temperature of 150℃ and a pressure of 2MPa using a compression molding machine. After being taken out, it was further heated in a dryer at a temperature of 180℃ for 1 hour to thermally cure the adhesive layer. In this way, a disc-shaped test piece with a diameter of 50mm and a thickness of 5mm was obtained.

For this specimen, the thermal conductivity (W/(m.K)) was measured using a thermal conductivity measuring device (trade name: HC-110, manufactured by Eiko Seiki Co., Ltd.) by the heat flow meter method (in accordance with JIS-A1412 (2016)).

[Implementation Example 1]

56 parts by mass of triphenylmethane epoxy resin (trade name: EPPN-501H, weight average molecular weight: 1000, softening point: 55°C, solid, epoxide equivalent: 167, manufactured by Nippon Kayaku Co., Ltd.), 49 parts by mass of bisphenol A epoxy resin (trade name: YD-128, weight average molecular weight: 400, softening point: below 25°C, liquid, epoxide equivalent: 190, manufactured by NSCC Epoxy Manufacturing Co., Ltd.), 30 parts by mass of bisphenol A phenoxy resin (trade name: YP-50, weight average molecular weight: 70000, Tg: 84°C, manufactured by NSCC Epoxy Manufacturing Co., Ltd.) and 103 parts by mass of MEK were heated and stirred at 110°C in a 1000 ml separable flask for 2 hours. In this way, resin varnish is obtained.

Next, 237 parts by mass of the resin varnish was transferred to an 800 ml planetary mixer, 196 parts by mass of an alumina filler (trade name: AO-502, true sphericity 0.99, average particle size (d50): 0.5 μm, manufactured by Admatechs) was added, and 2.0 parts by mass of an imidazole type hardener (trade name: 2PHZ-PW, manufactured by Shikoku Chemical Co., Ltd.) and 3.0 parts by mass of a silane coupling agent (trade name: S-510, manufactured by JNC) were added, and after stirring and mixing at room temperature for 1 hour, vacuum defoaming was performed to obtain a mixed varnish.

Then, the obtained mixed varnish was coated on a 38μm thick PET film (peel film) that had been subjected to mold release treatment, and dried at 130°C for 10 minutes to obtain a film-like adhesive having an adhesive layer of 300mm in length, 200mm in width, and 20μm in thickness on the PET film.

[Example 2]

The blending amount of the aluminum oxide filler was set to 305 parts by mass. The film adhesive of Example 2 was obtained in the same manner as Example 1.

[Implementation Example 3]

The blending amount of the aluminum oxide filler was set to 457 parts by mass. In addition, the film adhesive of Example 3 was obtained in the same manner as Example 1.

[Implementation Example 4]

The film adhesive of Example 4 was obtained in the same manner as Example 2 except that 120 parts by mass of an acrylic polymer solution (trade name: S-2060, mass average molecular weight: 500000, Tg: -23°C, solid content 25% (organic solvent: toluene), manufactured by Toagosei Co., Ltd.) (of which 30 parts by mass of acrylic polymer) was used to replace the bisphenol A type phenoxy resin.

[Implementation Example 5]

169 parts by mass of aluminum nitride filler (trade name: TFZ-A02P, sphericity 0.65, average particle size (d50): 1.1 μm, manufactured by Toyo Aluminum Co., Ltd.) was used to replace the aluminum oxide filler. The film adhesive of Example 5 was obtained in the same manner as Example 1.

[Implementation Example 6]

The film adhesive of Example 6 was obtained in the same manner as Example 5 except that the blending amount of aluminum nitride filler was changed to 263 parts by mass.

[Implementation Example 7]

The film adhesive of Example 7 was obtained in the same manner as Example 5 except that the blending amount of aluminum nitride filler was changed to 394 parts by mass.

[Implementation Example 8]

332 parts by mass of silver-coated polysilicone filler (trade name: SC0280-SF, sphericity 0.98, average particle size (d50): 5.8μm, manufactured by Mitsubishi Materials Corporation) was used to replace the alumina filler. The film adhesive of Example 8 was obtained in the same manner as Example 1.

[Example 9]

656 parts by mass of silver filler (trade name: AG-4-54F, sphericity 0.86, average particle size (d50): 2.0 μm, manufactured by DOWA Electronics) was used instead of the alumina filler. The film adhesive of Example 9 was obtained in the same manner as Example 1.

[Implementation Example 10]

688 parts by mass of nickel filler (trade name: CN050, sphericity 0.92, average particle size (d50): 3.0 μm, manufactured by NIKKO RICA) was used to replace the alumina filler. The film adhesive of Example 10 was obtained in the same manner as Example 1.

[Example 11]

The film adhesive of Example 11 was obtained in the same manner as Example 1, except that the blending amount of the aluminum oxide filler was set to 465 parts by mass and the blending amount of the imidazole hardener was set to 4.0 parts by mass.

[Comparison Example 1]

196 parts by mass of an alumina filler (trade name: SA32, sphericity 0.57, average particle size (d50): 1.0 μm, manufactured by Nippon Light Metals Co., Ltd.) was used as the alumina filler. In addition, the film adhesive of Comparative Example 1 was obtained in the same manner as in Example 1.

[Comparison Example 2]

The film adhesive of Comparative Example 2 was obtained in the same manner as Comparative Example 1 except that the blending amount of the alumina filler was set to 457 parts by mass.

[Comparison Example 3]

196 parts by mass of alumina filler (trade name: A33F, sphericity 0.59, average particle size (d50): 2.0 μm, manufactured by Nippon Light Metals Co., Ltd.) was used as alumina filler. In addition, the film adhesive of Comparative Example 3 was obtained in the same manner as Example 1.

[Comparison Example 4]

The film adhesive of Comparative Example 4 was obtained in the same manner as Comparative Example 3 except that the blending amount of the alumina filler was set to 457 parts by mass.

[Comparison Example 5]

656 parts by mass of silver filler (trade name: AgC-204B, sphericity 0.57, average particle size (d50): 2.0 μm, manufactured by Fukuda Metal Foil Co., Ltd.) was used to replace the alumina filler. In addition, the film adhesive of Comparative Example 5 was obtained in the same manner as Example 1.

[Comparison Example 6]

688 parts by mass of nickel filler (trade name: Type 255, sphericity 0.41, average particle size (d50): 2.5 μm, manufactured by NIKKO RICA) was used to replace the alumina filler. The film adhesive of Comparative Example 6 was obtained in the same manner as in Example 1.

[Comparison Example 7]

The film adhesive of Comparative Example 7 was obtained in the same manner as Example 1 except that the blending amount of the aluminum oxide filler was set to 214 parts by mass and the blending amount of the imidazole type hardener was set to 15.0 parts by mass.

[Comparison Example 8]

The blending amount of the aluminum oxide filler was set to 205 parts by mass, and the blending amount of the imidazole type hardener was set to 8.5 parts by mass. In addition, the film adhesive of Comparative Example 8 was obtained in the same manner as Example 1.

[Comparison Example 9]

200 parts by mass of acrylic polymer solution (trade name: TEISANRESIN SG-600TEA, mass average molecular weight: 1200000, Tg: -36°C, solid content 15% (organic solvent: toluene-ethyl acetate mixed solvent), manufactured by Nagase ChemteX) (of which 30 parts by mass of acrylic polymer) were used to replace bisphenol A type phenoxy resin. In addition, the film adhesive of Comparative Example 9 was obtained in the same manner as Example 1.

Regarding the film-like adhesives with peeling films of Examples 1 to 11 and Comparative Examples 1 to 9, their compositions, properties, and evaluation results are shown in the table below.

<Notes on the table>

A blank column in the inorganic filler (D) column means that the component is not contained.

"Inorganic filler amount [vol%]" refers to the ratio (volume %) of the inorganic filler (D) to the total content of the epoxy resin (A), polymer component (C), inorganic filler (D) and epoxy resin hardener (B).

The detection time of the heat peak in the DSC measurement at 120°C of the film adhesives of Comparative Examples 1 to 6 and Comparative Example 9 meets the requirements of the present invention, but the capillary rheometer viscosity is higher than the requirements of the present invention. On the contrary, the capillary rheometer viscosity of Comparative Examples 7 and Comparative Examples 8 is within the requirements of the present invention, but the detection time of the heat peak in the DSC measurement at 120°C is shorter than the requirements of the present invention. When the film adhesives of these comparative examples are used as die bonding films, after the die bonding step, even if the pressurized curing time using a pressurized oven is set to 90 minutes, the discharge of the voids is not sufficient.

In contrast, when the film adhesives of Examples 1 to 11 that meet the requirements of the present invention are used as die bonding films, even if the pressurized curing time using a pressurized oven is set to less than 90 minutes after the die bonding step, the voids can be completely removed. In addition, the film adhesives contain a large amount of fillers and exhibit sufficiently high thermal conductivity.

The present invention has been described in conjunction with the embodiments of the present invention, but the applicant believes that, unless otherwise specified, there is no intention to limit the present invention in any detail of the description, and it should be interpreted broadly without violating the spirit and scope of the invention as shown in the attached invention application patent scope.

This application claims priority based on patent application No. 2021-116012 filed in Japan on July 13, 2021, which is incorporated herein by reference and its contents as part of the description of this specification.

Claims (9)

A heat conductive film adhesive comprises an epoxy resin (A), an epoxy resin hardener (B), a polymer component (C) and an inorganic filler (D), wherein the epoxy resin hardener (B) contains an imidazole compound, the inorganic filler (D) has a true sphericity of 0.6-1.0, a capillary rheometer viscosity of 1-1000 Pa‧s at a temperature of 120°C and a load of 20 kg, and a detection time of a heat peak in differential scanning calorimetry at 120°C of more than 15 minutes. The heat conductive film adhesive of claim 1, wherein the ratio of the inorganic filler (D) to the total content of the epoxy resin (A), the epoxy resin curing agent (B), the polymer component (C) and the inorganic filler (D) is 30-70 volume %, and after thermal curing, a cured body with a thermal conductivity of 1.0 W/m‧K or more is provided. For thermally conductive film adhesives in claim 1 or 2, the thickness is 1~20μm. The heat conductive film adhesive of claim 1, wherein the content of the epoxy resin hardener (B) is 0.5-7 parts by mass relative to 100 parts by mass of the epoxy resin (A). A dicing die attach film is formed by laminating a dicing film and a thermally conductive film-like adhesive of any one of claims 1 to 4. A method for manufacturing a semiconductor package, comprising: a first step of hot-pressing a heat-conductive film adhesive of any one of claims 1 to 4 onto the back side of a semiconductor wafer having at least one semiconductor circuit formed on the surface, and providing a wafer-cutting film via the heat-conductive film adhesive layer; a second step of obtaining a semiconductor chip with an adhesive layer attached on the wafer-cutting film by integrally cutting the semiconductor wafer and the adhesive layer; a third step of removing the wafer-cutting film from the adhesive layer, and hot-pressing the semiconductor chip with the adhesive layer attached to a wiring board via the adhesive layer; and a fourth step of thermally curing the adhesive layer. The manufacturing method of semiconductor package as claimed in claim 6, wherein the first step is to hot press the wafer bonding film of claim 5 to the back side of the semiconductor wafer. A method for manufacturing a semiconductor package as claimed in claim 6 or 7, wherein the thermal curing in the above-mentioned step 4 is performed in a pressurized oven set at 100-150°C. A semiconductor package obtained by the manufacturing method of claim 6 or 7.